On the Cause of Explosions in Lamps. 319 
this point ; for besides the greater part of the two gallons 
of oil, a portion of which was in the lamp at the time of ex- 
plosion, the brasswork and fragments of the lamp had been 
forwarded to me, and I was thus enabled, after fitting on 
another glass body to experiment on what might be con- 
sidered as the original lamp and original oil, and found by 
actual observations with thermometers, introduced through 
holes bored in the sides of the lamp, that the oil in the 
interior rose no higher than 78 degrees, even after five hours 
burning in an unusually warm room. On applying a light, 
however, at this temperature, toan opening in the lamp, an 
explosion ensued. In short, it was found that even when 
the oil in the lower part of the body of the lamp was not 
warmer than 65 degrees, a mixture of vapour and air had 
formed in the upper part of the body, and exploded on a 
flame being introduced. Here, then, was a sample of oil, a 
portion of which had been the source of an explosion under 
ordinary domestic circumstances, which emitted no in- 
flammable vapour under 83 degrees, when tried outside the 
lamp, and yet which inside the lamp gave, at 60 to 70 de- 
grees, such a mixture of vapour and air that, should it catch 
fire, would inevitably explode. The explanation of this state 
of things was obvious. The oil, though at 75, 65, or even 
colder, had, in its passage up the wick to pass through the 
heated brasswork, the temperature of the gateway of which, 
the temperature of that part presented to the interior of the 
lamp, must have been high enough to cause the evolution 
of vapour into the air in the upper part of the interior. This 
temperature was taken by appropriate means and found to 
be 108 degrees ; ina smaller lamp it was 105, and in other 
experiments varied from 100 to IIo degrees during an 
evening. The cause of the explosion was thus perfectly 
clear. An oil giving inflammable vapour at 83 degrees, and 
not apparently heated beyond 60 to 70 degrees, had actually 
been exposed, in a most complete manner, to a temperature 
of 108 degrees, resulting in the formation of an explosive 
mixture, which accidently ignited on turning downthe wick. 
Every person who had used this oil in a paraffin lamp of 
the usual form had, so to speak, been burning his candle 
over acharge of gunpowder, and were it not that the chances 
of the explosive mixture becoming ignited were exceedingly 
small, as will be presently shown, many explosions, before 
that now recorded, must have attended the use of the oil. 
So, then, an oil giving inflammable vapour below 110 de- 
grees, and burnt in a lamp of ordinary construction, yields, 
